Various types of separators are known in the prior art. For example, a weir separator can be utilized to remove a fluid from another fluid having a greater density. Such a type of separator can, additionally, be employed for removing a solid, having a density lower than that of the liquid with which it is mixed, from the liquid.
Such a separator is only illustrative of many types that are currently available. As previously indicated, numerous configurations can be achieved, and the type of separator selected will depend upon the mixture components to be segregated.
The present invention specifically deals with a separator known as a "cyclone" separator. Such separators typically have a generally cylindrical separation chamber which is disposed above a collection chamber. The collection chamber tends to be conical with its wall tapering, concurrently, downwardly and inwardly with respect to the axis of the cone. The cone is typically truncated at the bottom, and means are provided at the truncation for conveying particulate matter separated from a gas introduced into the separation chamber away from the collection chamber.
The gas is accelerated to an intended velocity in some manner and tangentially injected into the separation chamber through an inlet thereto. The inlet, typically, extends in height from an upper edge of the separation chamber, downwardly along a side, generally circular cylindrical wall of that chamber.
One of two types of inlets are usually employed, although a third type is encountered on occasion. The first, known as an inside tangent inlet, is one wherein the full width of fluid flow through the inlet merges immediately with centrifugal flow occurring within the separation chamber as tangential insertion is effected. The second, known as an outside tangent inlet, is one wherein the width of fluid flow through the inlet is gradually merged with the centrifugal flow within the chamber. That is, the inlet extends, for example, through about 180.degree. about the separation chamber, an outer wall of the inlet tapering inwardly toward the generally circularly cylindrical wall of the separation chamber. The third type is a hybrid of the first two types and has some of the features and performance characteristics of both inside tangent and outside tangent inlets.
While in the first type significant turbulence is created because of the full merging of the fluid entering in through the inlet, less turbulence is created in cyclones of the second type. It should be understood, however, that, even in the second type of cyclone, turbulence is created as the gas, entraining particulate matter therein, is merged into the separation chamber.
Generally centrally disposed within the cylindrical wall defining the separation chamber is what, in the industry, is referred to as a vortex finder. The vortex finder is, in effect, an egress conduit for fluid from which particulate matter has been separated. The gaseous fluid passing through the vortex finder is, in turn, recovered and stored in an appropriate container.
In operation, air passes through the inlet, regardless of what type of inlet is employed, and into the separation chamber. Movement of the air through the inlet is accomplished in any appropriate manner employing acceleration means external to the cyclone. That is, the fluid entraining the particulate matter can be driven into the separation chamber from the inlet end or drawn into the chamber through the inlet by employment of, for example, vacuum generation means downstream of the egress conduit. In either case of flow generation, however, it will be understood that a cyclone employs no moving parts.
Once the fluid flow enters through the inlet, it will pass circumferentially through an annular space between the vortex finder and the cylindrical wall of the separation chamber. The particulate matter entrained within the gas, being greater in density than the gas in which it is entrained, will be urged radially outwardly against the cylindrical side wall of the separation chamber. The gas in which the matter was entrained will tend to rotate about the vortex finder radially more inward.
As additional gas to be purged of the particulate matter flows into the separation chamber, accumulation of gas will tend to fill the annular base between the vortex finder and the cylindrical wall of the chamber. Eventually, the build-up will be sufficient so that the gas will enter the vortex finder and be vented. This effect is furthered by the fact that, the gas being radially inwardly from the cylindrical side wall of the chamber, it will rotate at a greater velocity and will tend to spiral over into the vortex finder.
The particulate matter, having been centrifugally impelled radially outwardly, continues to rotate along the inner surface of the cylindrical side wall of the separation chamber. As such matter builds up as additional fluid passes through the separator, increased friction created by engagement of the matter with the inner surface of the wall will cause the particles to slow down in their rotation and, commensurately, settle downwardly.
As previously discussed, a collection chamber, typically conical in shape, is disposed beneath the separation chamber. Particulate matter passing downwardly within the separation chamber will, therefore, enter the collection chamber and be funneled to a discharge for removal.
Performance of cyclone separators is measured in terms of minimization of pressure drop and collection efficiency. The former factor bears upon power requirements for generation of flow through the separator, and the longevity of equipments employed for generating flow. The latter factor is measured by the percentage of particulate matter actually moved from the fluid. High removal percentages are inhibited by the fact that, if there is significant turbulence in the circumferential flow, more matter will tend to remain radially inwardly rather than being impelled centrifugally outward. Additionally, if good flow patterns are not facilitated, a column of particulate matter may rise upwardly through the vortex finder from a location at the bottom of the collection chamber where it might have briefly accumulated.
Similarly, turbulence has a bearing upon minimization of pressure drop. It is axiomatic that, the greater the turbulence, the greater will be the pressure drop.
It is to these considerations dictated by the prior art that the present invention is directed. It is an apparatus which reduces pressure drop significantly in a cyclone separator and which maximizes particulate matter collection.